<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      ul li {
        list-style: none;
      }
      ul {
        float: left;
      }
      li {
        position: relative;
        float: left;
        width: 70px;
        height: 30px;
        line-height: 30px;
        text-align: center;
        background-color: #cecece;
        border: 2px solid #000;
      }
      a {
        position: absolute;
        top: 12px;
        border: 10px solid transparent;
        border-bottom: 0;
        border-top-color: #000;
      }
      li:hover {
        cursor: pointer;
        color: yellowgreen;
      }
      li:hover > a {
        cursor: pointer;
        border-top-color: yellowgreen;
      }
    </style>
  </head>
  <body>
    <ul>
      <li>点击<a href="#"></a></li>
      <li></li>
      <li></li>
      <li></li>
      <li></li>
    </ul>
  </body>
</html>
